Project Summary/Abstract: This project will examine the coordination of cellular events during gametogenesis. During gamete formation, cells must coordinate the complex events that occur during meiosis and gamete differentiation. Meiosis involves the cellular events that occur as cells undergo the reductional divisions necessary to create haploid nuclei from a diploid cell. Gamete formation requires extensive changes to cell morphology, and these morphological changes must be coordinated with meiosis as cells differentiate. In the budding yeast Saccharomyces cerevisiae, gametogenesis occurs through the process of sporulation. During sporulation, meiotic cytokinesis involves the formation of the prospore membrane, which grows to surround and eventually enclose the meiotic nucleus; eventually, the prospore membrane becomes the plasma membrane of the newly formed cells. Our long-term goal is to understand prospore membrane development in order to gain fundamental knowledge about how complex cellular events are coordinated. Because the prospore membrane is critical for the life cycle of fungal pathogens, these studies may also provide insights into fungal-specific mechanisms that can be targeted to combat pathogens that cause human disease. Our previous studies show that timely closure of the prospore membrane requires the STE20 GC family kinase encoded by SPS1, which acts with SPO77 and in parallel to AMA1 (which encodes the meiotic activator of the anaphase promoting complex). We found that SPS1 acts to regulate prospore membrane closure through the PI(4,5) binding protein Ssp1, affecting the stability and phosphorylation of Ssp1. Experiments in this proposal extend our previous work, focusing on how prospore membrane closure is coordinated. Aim 1 examines genes known to act in prospore membrane closure and analyzes their relationship with regulators of meiosis. Aim 2 seeks to more broadly examine the relationship between PSM closure and the cellular events occurring during meiotic exit.